Did you restart whatever was serving your PHP yesterday?
Which localhost are you using? XAMPP, WAMP, MAMP (Mac)?
Which operating system? Win (version), Mac (version), Linux?
“Can’t open” what, exactly?
What error(s) are you getting?
Is your localhost still running? Does it’s “indicators” say so?
What do you get if you enter just http://localhost ?
Please provide as much info as possible 🙂
